APPLIED GEOPHYSICS FOR ENGINEERING PROBLEMS

THE APPLICATION OF GEOPHYSICS TO THE STUDY OF MATERIALS AND RIPPABILITY ALONG A PROPOSED MOUNTAIN- STANDARD ROAD ALIGNMENT, AND TO THE STUDY OF A SITE FOR ITS RESPONSE TO NATURAL VIBRATIONS AND EARTHQUAKE MOTION IS DESCRIBED. IN THE MOUNTAIN-STANDARD ROAD PROJECT, SEISMIC REFRACTION SURVEY DETERMINED THE DEPTH OF RIPPABLE AND TO SOME DEGREE THE DEPTH OF UNSTABLE MATERIALS IN THE CUT SECTION AREAS OF THE ALIGNMENT. THE ENGINEERING GEOLOGIST TOGETHER WITH THE GEOPHYSICISTS COULD COMPARE THE LOCAL GEOLOGY TO THE SEISMIC RECORDS AND INTERPRET AND MAKE DECISIONS IN THE FIELD. DETERMINATIONS OF DEPTHS TO EACH OF THE REFRACTOR SURFACES COULD BE COMPARED WITH GEOLOGICAL JUDGEMENT. GRAPHS ILLUSTRATE THE RESULTS OF TESTS. IN THIS PROJECT, KNOWLEDGE OF THE EXCAVATABILITY AND INSTABILITY OF MATERIALS CONTRIBUTED TO THE DESIGN PROCESS, AND MAJOR CHANGES IN GRADE AND ALIGNMENT BASED ON GEOLOGICAL AND GEOPHYSICAL INPUT WERE EFFECTED. IN AN EARTHQUAKE RESISTANCE DESIGN PROJECT, DETAILS OF A METHOD OF ON-SITE RECORDING OF GROUND ACCELERATION, AND ANALYSIS OF THE DIGITIZED ACCELEROGRAM BY A DIGITAL COMPUTER ARE DESCRIBED. SYSTEMATIC OBSERVATION OF MICROTREMORS WAS CARRIED OUT. DETAILS OF THE INSTRUMENT PACKAGE WHICH MUST BE PORTABLE, RELIABLE, AND VERY SENSITIVE ARE DESCRIBED. AFTER RECORDING OF THE ACCELEROGRAM, THE DATA WHICH IS REDUCED IN A 2-PROGRAM PROCESS, GIVES INFORMATION OF THE PREDOMINANT NATURAL GROUND FREQUENCIES OR PERIODS. THE INFORMATION COULD BE USED TO DESIGN A STRUCTURE WHOSE FUNDAMENTAL FREQUENCY IS NOT NEAR THE PEAKS IN THE GROUND SPECTRA (MAY NOT BE PRACTICAL), OR IN THE USE OF ANOTHER METHOD IN WHICH THE STANDARD FORMULA FOR BASE SHEAR IS MODIFIED.

Media Info

  • Features: Figures;
  • Pagination: p. 243-55

Subject/Index Terms

Filing Info

  • Accession Number: 00230157
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Dec 4 1973 12:00AM